Basement insulation above and below grade mix

Arogo

New Member
Nov 4, 2020
1
Worcester, MA
Related to this old thread - https://www.hearth.com/talk/threads/ok-to-put-foam-board-over-top-of-fiberglass-batts.8725/post-265654

My basement is a mix of 1) below grade cement walls and 2) above grade studded walls (think of half wall in basement where bottom half is cement and below grad and top half is studded out).

i lost track in above thread with which answers were to which posts, so asking (again) specific to my situation for advice.
For my (1) arrangement above, is this the suggested best game plan do inside finishing: foam board polyiso directly against cement walls, then wood studded wall with unbatted fiberglass, then drywall? No plastic vapor barrier anywhere here, right? So it would go (outside-in): cement, foam board, studs with unbatted fiberglass, drywall)?
For my (2) arrangement above, the studded walls already have batted fiberglass in them (paper side facing exterior wall/siding and plastic barrier on inside attached to studs (barrier is pretty banged up after 20 yrs). Could foam board polyiso be installed directly on top of studs (keep existing vapor barrier/plastic sheet, replace with new one, or remove?), and then drywall on top of foam board? So I would go exterior wall, studded wall with batted fiberglass, foam board, drywall (no separate plastic vapor barrier layer)?

yes I also plan to install foam board in rim joists on top of cement walls and seal those edges with spray foam, then stuff unbatted fiberglass in rest of cavity to come flush with new studded walls on interior. Right?
 

Bad LP

Minister of Fire
Nov 28, 2014
1,295
Northern Maine
Stud it out and spray closed cell foam is also an option. This solves your vapor barrier needs at the same time.